This invention relates to the treatment of hydrocarbon and carbon monoxide gases issuing from various sources one of which is the gases issuing from a catalytic converter connected to the exhaust of an internal combustion engine. More particularly, this invention is directed to apparatus positioned downstream of the primary catalytic converter of an internal combustion engine for supplementing the function of the catalytic converter and may be positioned in the gas stream before, in place of or after the muffler.
Current automotive catalytic converters comprise a multichannel substrate having flow-through channels which are coated with noble metal catalyst materials that convert the pollutant exhaust gases to harmless effluent.
The automotive catalytic converters generally comprise a large, oval-shaped ceramic substrate housed in a metal sleeve or can. The converters are connected directly to a manifold exhaust pipe of an internal combustion engine and normally discharge purified gases through a muffler to atmosphere.
The catalytic converter is designed to reduce hydrocarbon (HC) and carbon monoxide (C)) emissions into carbon dioxide and water vapor. The converter also purges oxides of nitrogen (NOx) vapors from the exhaust. It is called catalytic because precious-metal catalysts inside the converter react with these toxic gases on the large surface area of an ingenious honeycomb coated with less than a gram of the catalytic material.
Most vehicles made after 1980 use this so-called monolithic converter. Pre 1980 vintage cars have pellet-type converter. Pellet converters contain thousands of tiny grains of ceramic reactants that produce a similar result.
Although the catalytic converter has been successful in removing some of the hydrocarbons and carbon monoxide from the exhaust gases of internal combustion engines, there remains a need for removing still more of these toxic gases exiting from the exhaust of the catalytic converter as well as from other sources of air contamination.
This can be accomplished by incorporating an add-on supplemental converter before, after or in place of the muffler. Such an add-on converter will further process the exhaust gases by passing them over a mineral substance that acts upon the remaining carbon monoxide and hydrocarbons, to further reduce the content of these substances in the exhaust gases.